APOD: Contemplating the Sun (2012 May 28)

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APOD: Contemplating the Sun (2012 May 28)

Post by APOD Robot » Mon May 28, 2012 4:11 am

Image Contemplating the Sun

Explanation: Have you contemplated your home star recently? Pictured above, a Sun partially eclipsed on the top left by the Moon is also seen eclipsed by earthlings contemplating the eclipse below. The above menagerie of silhouettes was taken from the Glenn Canyon National Recreational Area near Page, Arizona, USA, where park rangers and astronomers expounded on the unusual event to interested gatherers. Also faintly visible on the Sun's disk, just to the lower right of the dark Moon's disk, is a group of sunspots. Although exciting, some consider this event a warm-up act for next week's chance to comtemplate the Sun -- a much more rare partial eclipse by the planet Venus.

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Re: APOD: Contemplating the Sun (2012 May 28)

Post by Mactavish » Mon May 28, 2012 4:36 am

Great shot, Steven! This is something we seldom see in a space image. . .the human involvement in things astronomical. You captured it!

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Re: APOD: Contemplating the Sun (2012 May 28)

Post by starstruck » Mon May 28, 2012 7:17 am

This picture reminds me strongly of Pink Floyd on stage . . but, "Hey!, Teacher!", where's Dave?

Seriously though, what a superb photo! It really tells the story. I would love to know what the focal length of the lens used to take this photo was; the photographer must have been quite some considerable distance away from those figures on the skyline for the sun/moon to appear so large behind them. Great picture! :clap:

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Re: APOD: Contemplating the Sun (2012 May 28)

Post by orin stepanek » Mon May 28, 2012 11:31 am

Beautiful silhouette Steven! :thumb_up: :thumb_up: 8-)
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Re: APOD: Contemplating the Sun (2012 May 28)

Post by saturno2 » Mon May 28, 2012 12:27 pm

This is a beautiful image.
Surrealist picture. very well

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Re: APOD: Contemplating the Sun (2012 May 28)

Post by chrisathena » Mon May 28, 2012 2:05 pm

This is a great photo. Is it possible to share these on Facebook?

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Re: APOD: Contemplating the Sun (2012 May 28)

Post by biddie67 » Mon May 28, 2012 2:25 pm

Absolutely a fabulous and beautiful photo!!!! Congratulations!!!!

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Re: APOD: Contemplating the Sun (2012 May 28)

Post by owlice » Mon May 28, 2012 2:34 pm

chrisathena wrote:This is a great photo. Is it possible to share these on Facebook?
https://www.facebook.com/AstronomyPictureOfTheDay
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Venus Transit pairs

Post by neufer » Mon May 28, 2012 4:06 pm

http://en.wikipedia.org/wiki/Transit_of_Venus wrote: -----------------------------------
December: 1631 and 1639

<<In 1627, Johannes Kepler became the first person to predict a transit of Venus, by predicting the 1631 event. His methods were not sufficiently accurate to predict that the transit would not be visible in most of Europe, and as a consequence, nobody was able to make arrangements to observe the phenomenon.

The first known observation of a transit of Venus was made by Jeremiah Horrocks from his home at Carr House in Much Hoole, near Preston in England, on 4 December 1639 (24 November under the Julian calendar then in use in England). His friend, William Crabtree, also observed this transit from Broughton, near Manchester. Kepler had predicted transits in 1631 and 1761 and a near miss in 1639. Horrocks corrected Kepler's calculation for the orbit of Venus, realized that transits of Venus would occur in pairs 8 years apart, and so predicted the transit in 1639. Although he was uncertain of the exact time, he calculated that the transit was to begin at approximately 3:00 pm. Horrocks focused the image of the Sun through a simple telescope onto a piece of paper, where the image could be safely observed. After observing for most of the day, he was lucky to see the transit as clouds obscuring the Sun cleared at about 3:15 pm, just half an hour before sunset. Horrocks' observations allowed him to make a well-informed guess as to the size of Venus, as well as to make an estimate of the distance between the Earth and the Sun. He estimated that distance to be 59.4 million miles (95.6 Gm, 0.639 AU) – about two thirds of the actual distance of 93 million miles (149.6 million km) but a more accurate figure than any suggested up to that time. The observations were not published until 1661, well after Horrock's death.>>
-----------------------------------
June: 1761 and 1769

<<In 1663 Scottish mathematician James Gregory had suggested in his Optica Promota that observations of a transit of the planet Mercury, at widely spaced points on the surface of the Earth, could be used to calculate the solar parallax and hence the astronomical unit. Aware of this, a young Edmund Halley made observations of such a transit in 1676 from St Helena, but was disappointed to find that there had been only one other observation of the event and was not satisfied that the resulting calculation of the solar parallax at 45" was accurate. In 1678 he proposed that more accurate calculations could be made using measurements of a transit of Venus, although the next such event was not due until 1761. Halley died in 1742, but in 1761 numerous expeditions were made to various parts of the world so that precise observations of the transit could be made in order to make the calculations as described by Halley — an early example of international scientific collaboration. In an attempt to observe the first transit of the pair, scientists and explorers from Britain, Austria and France travelled to destinations around the world, including Siberia, Norway, Newfoundland and Madagascar. Most managed to observe at least part of the transit, but successful observations were made in particular by Jeremiah Dixon and Charles Mason at the Cape of Good Hope.

The unfortunate Guillaume Le Gentil spent eight years travelling in an attempt to observe either of the transits. His unsuccessful journey led to him losing his wife and possessions and being declared dead (his efforts became the basis of the play Transit of Venus by Maureen Hunter).

On the basis of his observation of the transit of Venus of 1761 from the Petersburg Observatory, Mikhail Lomonosov predicted the existence of an atmosphere on Venus. Lomonosov detected the refraction of solar rays while observing the transit and inferred that only refraction through an atmosphere could explain the appearance of a light ring around the part of Venus that had not yet come into contact with the Sun's disk during the initial phase of transit.

For the 1769 transit, scientists traveled to Hudson Bay (Canada), San José del Cabo (Baja California, then under Spanish control), and Norway. Observations were also made from Tahiti on the first voyage of Captain Cook, at a location still known as "Point Venus". The Czech astronomer Christian Mayer was invited by Catherine the Great to observe the transit in Saint Petersburg with Anders Johan Lexell, while other members of Russian Academy of Sciences went to eight other locations in the Russian Empire. In Philadelphia, the American Philosophical Society erected three temporary observatories and appointed a committee, of which David Rittenhouse was the head. The results of these observations were printed in the first volume of the Society's Transactions, published in 1771.

In 1771, using the combined 1761 and 1769 transit data, the French astronomer Jérôme Lalande calculated the astronomical unit to have a value of 153 million kilometers (±1 million km). The precision was less than hoped-for because of the black drop effect, but still a considerable improvement on Horrocks' calculations.
--------------------------------------------
December: 1874 and 1882

<<Unfortunately, it was impossible to time the exact moment of the start and end of the transit because of the phenomenon known as the "black drop effect". This effect was long thought to be due to Venus' thick atmosphere, and initially it was held to be the first real evidence that Venus had an atmosphere. However, recent studies demonstrate that it is an optical effect caused by the smearing of the image of Venus by turbulence in the Earth's atmosphere or imperfections in the viewing apparatus.

Transit observations in 1874 and 1882 allowed this value to be refined further. Several expeditions were sent to the Kerguelen Archipelago for the 1874 observations. The American astronomer Simon Newcomb combined the data from the last four transits, and he arrived at a value of about 149.59 million kilometers (±0.31 million kilometers). Modern techniques, such as the use of radio telemetry from space probes, and of radar measurements of the distances to planets and asteroids in the Solar System, have allowed a reasonably accurate value for the astronomical unit (AU) to be calculated to a precision of about ±30 meters. Hence the need for parallax calculations has been superseded.>>
--------------------------------------------
http://en.wikipedia.org/wiki/Guillaume_Le_Gentil wrote:

<<Guillaume Joseph Hyacinthe Jean-Baptiste Le Gentil de la Galaisière (Coutances, September 12, 1725 – Paris, October 22, 1792) was a French astronomer. He was born in Coutances and first intended to enter the church before turning to astronomy. He discovered what are now known as the Messier objects M32, M36 and M38, as well as the nebulosity in M8, and he was the first to catalogue the dark nebula sometimes known as Le Gentil 3 (in the constellation Cygnus).

He was part of the international collaborative project organized by Mikhail Lomonosov to measure the distance to the Sun, by observing the transit of Venus at different points on the earth. Edmond Halley had suggested the idea, but it required careful measurements from different places on earth, and the project was launched with more than a hundred observers dispatched to different parts of the globe, for observing the transit coming up in 1761. The French expedition turned out to be particularly unlucky, and perhaps the most unfortunate was Guillaume le Gentil, who set out for Pondicherry, a French colony in India.

He set out from Paris in March 1760, and reached Île de France (Mauritius) in July. But having learned that war had broken out between France and Britain, and deeming it dangerous to try to reach Pondicherry, he determined to go elsewhere; a frigate was bound for India's Coromandel Coast, and he sailed in March 1761. When they had nearly arrived they learned that the British had occupied Pondicherry, so the frigate was obliged to return to Île de France. June 6, the day of the transit, came, and the sky was clear, but he could not take astronomical observations with the vessel rolling about. After having come this far, he thought he might as well await the next transit of Venus, which would come in another eight years (they are relatively infrequent, occurring in pairs 8 years apart, but each such pair is separated from the previous and next pairs by more than a century.)
After spending some time mapping the eastern coast of Madagascar, he decided to record the 1769 transit from Manila in the Philippines. Encountering hostility from the Spanish authorities there, he headed back to Pondicherry, which had been restored to France by peace treaty in 1763, where he arrived in March 1768. He built a small observatory and waited patiently. At last, the day in question (June 4, 1769) arrived, but although the mornings in the preceding month had all been lovely, on this day the sky became overcast, and Le Gentil saw nothing. The misfortune drove him to the brink of insanity, but at last he recovered enough strength to return to France.

The return trip was first delayed by dysentery, and further when his ship was caught in a storm and dropped him off at Île Bourbon (Réunion), where he had to wait until a Spanish ship took him home. He finally arrived in Paris eleven years later in October 1771, only to find that he had been declared legally dead and been replaced in the Royal Academy of Sciences. His wife had remarried, and all his relatives had "enthusiastically plundered his estate". Lengthy litigation and the intervention of the king were ultimately required before things were normalized. He got back his seat in the academy, remarried, and lived apparently happily for another 21 years.

One of his interesting findings was that the duration of the lunar eclipse of 30 August 1765 was predicted by a Tamil astronomer, based on the computation of the size and extent of the earth-shadow (going back to Aryabhata, 5th c.), and was found short by 41 seconds, whereas the charts of Tobias Mayer were long by 68 seconds.>>
Art Neuendorffer

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Re: APOD: Contemplating the Sun (2012 May 28)

Post by ritwik » Mon May 28, 2012 4:30 pm

it's amazing we have accurate records of events happened ~500 years ago !!! we could give future generations HD videos for reference instead of crude paintings :)

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Re: APOD: Contemplating the Sun (2012 May 28)

Post by Chris Peterson » Mon May 28, 2012 4:50 pm

ritwik wrote:it's amazing we have accurate records of events happened ~500 years ago !!! we could give future generations HD videos for reference instead of crude paintings :)
Yeah, but those paintings, drawings, and books are readable today without any technology at all. Will future generations have any idea how to actually turn a video, or any other digital data, into something they can interpret? It's a serious concern.
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Re: APOD: Contemplating the Sun (2012 May 28)

Post by Ann » Mon May 28, 2012 8:01 pm

Chris Peterson wrote:
ritwik wrote:it's amazing we have accurate records of events happened ~500 years ago !!! we could give future generations HD videos for reference instead of crude paintings :)
Yeah, but those paintings, drawings, and books are readable today without any technology at all. Will future generations have any idea how to actually turn a video, or any other digital data, into something they can interpret? It's a serious concern.
That reminds me of a golden long-playing record that was put inside one of the earliest probes that was going to leave the Solar system and end up in interstellar space. The record was included for the benefit of any aliens that might encounter the Earthly spacecraft, and by playing the record the aliens could learn a lot about the civilization that sent the probe into space.

Of course, E.T. and his friends would have to invent the record player before they could learn much at all from that golden record from the Earth!

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Re: APOD: Contemplating the Sun (2012 May 28)

Post by Case » Mon May 28, 2012 8:10 pm

Ann wrote:Of course, E.T. and his friends would have to invent the record player before they could learn much at all from that golden record from the Earth!
The Voyager Golden Records do contain playback instructions.
physics.stackexchange.com/questions/25711/where-are-the-voyagers-going wrote:In about 40,000 years, Voyager 1 will drift within 1.6 light years (9.3 trillion miles) of AC+79 3888, a star in the constellation of Camelopardalis. In some 296,000 years, Voyager 2 will pass 4.3 light years (25 trillion miles) from Sirius, the brightest star in the sky . The Voyagers are destined —perhaps eternally— to wander the Milky Way.

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Re: APOD: Contemplating the Sun (2012 May 28)

Post by Beyond » Mon May 28, 2012 9:36 pm

Contemplate the sun. Hmm... warm, bright, beats useing a candle or flashlight, emits hazardous radiation at us, especially when it's having blemish problems. I say lets turn it off and tweak it to be more human friendly. Anyone have a sun-adjuster tool-kit :?: :?:
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Re: APOD: Contemplating the Sun (2012 May 28)

Post by Moonlady » Tue May 29, 2012 1:23 am

Beyond wrote:Contemplate the sun. Hmm... warm, bright, beats useing a candle or flashlight, emits hazardous radiation at us, especially when it's having blemish problems. I say lets turn it off and tweak it to be more human friendly. Anyone have a sun-adjuster tool-kit :?: :?:

No, it is not the sun, it is the same banana like on 22th May 2012 only in b/w. :wink:

However...it is a very beautiful picture!

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Re: APOD: Contemplating the Sun (2012 May 28)

Post by James86004 » Tue May 29, 2012 3:58 pm

Nice image. One small misspelling - Glen in Glen Canyon only has one "n".

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Re: APOD: Contemplating the Sun (2012 May 28)

Post by geckzilla » Fri Jun 01, 2012 1:20 pm

Chris Peterson wrote:
ritwik wrote:it's amazing we have accurate records of events happened ~500 years ago !!! we could give future generations HD videos for reference instead of crude paintings :)
Yeah, but those paintings, drawings, and books are readable today without any technology at all. Will future generations have any idea how to actually turn a video, or any other digital data, into something they can interpret? It's a serious concern.
And when they do, there's a chance that any random thing they do manage to interpret will be something from the unimaginably large volume of smut that a good portion of the male population has stored digitally. ... :facepalm: :lol2:
Just call me "geck" because "zilla" is like a last name.

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Re: APOD: Contemplating the Sun (2012 May 28)

Post by bystander » Fri Jun 01, 2012 1:29 pm

geckzilla wrote:And when they do, there's a chance that any random thing they do manage to interpret will be something from the unimaginably large volume of smut that a good portion of the male population has stored digitally. ... :facepalm: :lol2:
I don't think you give your gender enough credit. They probably have a sizable collection, themselves. :shock: :P
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Re: APOD: Contemplating the Sun (2012 May 28)

Post by geckzilla » Fri Jun 01, 2012 1:50 pm

bystander wrote:
geckzilla wrote:And when they do, there's a chance that any random thing they do manage to interpret will be something from the unimaginably large volume of smut that a good portion of the male population has stored digitally. ... :facepalm: :lol2:
I don't think you give your gender enough credit. They probably have a sizable collection, themselves. :shock: :P
If I had to guess, though, I'd say ours is more the size of Venus while yours is the size of Jupiter. Wikipedia is probably larger than ours. Wow, I wonder if anyone has ever tried to make a serious pie chart for what the internet contains?
Just call me "geck" because "zilla" is like a last name.

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Re: APOD: Contemplating the Sun (2012 May 28)

Post by rstevenson » Fri Jun 01, 2012 3:49 pm

You mean there are more things on the web than APOD and Wikipedia?!?

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Re: APOD: Contemplating the Sun (2012 May 28)

Post by Chris Peterson » Fri Jun 01, 2012 3:58 pm

geckzilla wrote:If I had to guess, though, I'd say ours is more the size of Venus while yours is the size of Jupiter.
Geez... after introducing porn into the discussion, just how do you expect a statement like that to be interpreted?!
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Re: APOD: Contemplating the Sun (2012 May 28)

Post by neufer » Fri Jun 01, 2012 4:27 pm

Chris Peterson wrote:
geckzilla wrote:
If I had to guess, though, I'd say ours is more the size of Venus while yours is the size of Jupiter.
Geez... after introducing porn into the discussion,
just how do you expect a statement like that to be interpreted?!
I'm sure the reference isn't to you personally, Chris.
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Re: APOD: Contemplating the Sun (2012 May 28)

Post by geckzilla » Fri Jun 01, 2012 7:21 pm

I'm the only person at this board who still laughs at Uranus jokes. You expect me to hold back on others?
Just call me "geck" because "zilla" is like a last name.

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Re: APOD: Contemplating the Sun (2012 May 28)

Post by Beyond » Fri Jun 01, 2012 7:27 pm

geckzilla wrote:I'm the only person at this board who still laughs at Uranus jokes. You expect me to hold back on others?
Geckzilla, i like Uranus jokes. But i appreciate them more from the upwind side.
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Re: APOD: Contemplating the Sun (2012 May 28)

Post by neufer » Fri Jun 01, 2012 8:14 pm

geckzilla wrote:
I'm the only person at this board who still laughs at Uranus jokes.
Way to kick a planet when it is down. :evil:
http://www.universetoday.com/16940/ten-mysteries-of-the-solar-system/ wrote:
<<Some scientists believe that Uranus was the victim of a cosmic hit-and-run, but others believe there may be a more elegant way of describing the gas giant’s strange configuration. Early in the evolution of the Solar System, astrophysicists have run simulations that show the orbital configuration of Jupiter and Saturn may have crossed a 1:2 orbital resonance. During this period of planetary upset, the combined gravitational influence of Jupiter and Saturn transferred orbital momentum to the smaller gas giant Uranus, knocking it off-axis. More research needs to be carried out to see if it was more likely that an Earth-sized rock impacted Uranus or whether Jupiter and Saturn are to blame. >>
http://www.newscientist.com/article/dn18239-large-moon-of-uranus-may-explain-odd-tilt.html wrote:

Large moon of Uranus may explain odd tilt

<<Please try to resist the childish jokes, but the fact is that the odd tilt of Uranus may be the result of a particularly large moon. Uranus spins on an axis almost parallel with the plane of the solar system, rather than perpendicular to it – though why it does this nobody knows. One theory is that the tilt is the result of a collision with an Earth-sized object, but this "hasn't succeeded in explaining much of anything", says Ignacio Mosqueira of the SETI Institute in Mountain View, California. Why, for example, are the orbits of Uranus's 27 known moons not also tilted?

Now Gwenaël Boué and Jacques Laskar at the Paris Observatory in France have come up with another explanation: Uranus may once have had an unusually massive extra moon. If the moon had 1 per cent of the mass of Uranus – and orbited at a certain distance – it would slightly unbalance the planet and increase its wobble about its axis. After about 2 million years, the wobbling could have become exaggerated enough to tip the planet on its side, their model has shown (arxiv.org/abs/0912.0181). The moon may since have been ejected by the tug of another planet passing nearby. Its fate is unclear, but it may have crashed into another gas giant if it is not still roaming the solar system.

William Ward at the Southwest Research Institute in Colorado finds the theory plausible but points out there is no evidence for the extra moon other than the effect Boué and Laskar suggest it has had on Uranus's orientation.>>
http://news.discovery.com/space/has-the-mystery-of-uranus-tilt-been-solved.html wrote:
Has the Mystery of Uranus' Tilt Been Solved?
Analysis by Ian O'Neill
Sun Dec 6, 2009 12:09 AM ET

<<One of the most enduring mysteries of the Solar System may be a step closer to being solved. Although the general consensus is that Uranus was involved in some kind of cosmic hit-and-run, two researchers from Paris think the gas giant may have gradually wobbled over millions of years, eventually tipping due to the presence of a large moon.

It is well known that Uranus is an oddball, orbiting around the sun on its side, but little is known how the huge planet came to be this way. Usually the planets orbit the sun upright, with the axis of rotation perpendicular to the solar system's plane (i.e. in relation to Earth, pointing "north"). That is, apart from Venus and Uranus. Venus, however, is a more extreme case, where the entire planet was turned upside down, causing it to rotate in an opposite fashion to Earth. Uranus is tilted 97 degrees to the vertical. The Earth's tilt is a little over 23 degrees, and it is this tilt that gives our planet seasons. Needless to say, the seasons on Uranus are a little more extreme than ours; each Uranian hemisphere experiences 42 years of continuous sunlight (a year on Uranus is 84 Earth years).

This is all very interesting, but how did Uranus come to be this way? After all, the planet is really big (14.5 times the mass of Earth), it would take some kind of cataclysmic event to knock it on its side (it is impossible for the planet to be "born" this way, it should have an upright axis like all the other planets). Generally it is assumed that another planet must have collided with Uranus, pushing it off-kilter, but new computer models suggest a scenario that is far more elegant.

Gwenaël Boué and Jacques Laskar from the Paris Observatory in France started out with the idea that Uranus may have once had a very large moon, approximately one percent of the gas giant's mass. Through the gravitational "tugging" by the large moon's mass, over the course of 2 million years Uranus may have wobbled to such an extent that it was pulled onto its side. However, the researchers admit that such a large moon may not be plausible as current satellite formation models don't allow moons of this size. As indicated in their unpublished paper's conclusions, a smaller satellite of only 0.1 percent the mass of Uranus may be sufficient to pull the planet on its side over a longer period.

But what happened to this moon? It is not uncommon that planets disrupt (or even steal) other planet's moons, so the gravitational influences of the other massive gas giants may be a factor. For example, Neptune's large moon Triton is thought to have been "kidnapped" from the Kuiper Belt as it has a retrograde orbit (i.e. it orbits the "wrong way" when compared with the other Neptunian moons) and it has a similar composition to the dwarf planet Pluto. Perhaps a massive moon orbited Uranus long enough to wobble the planet onto its side, only for the satellite itself to be kicked out of orbit by a passing planet.

Although the jury is likely to be out for the foreseeable future as to the mechanism that knocked Uranus onto its side, this collisionless scenario is a fresh look at an old mystery that will continue to fox astronomers for some time yet.>>
Art Neuendorffer